Ellis f



(No Model.)

- E. I. FROST.

TELEPHONY. .No. 537,282, Patented Apr. 9, 1895.

UNITED STATES Y PATENT OFFICE.

ELLIS F. FROST, OF WASHINGTON, DISTRICT OF COLUMBIA.

TELEPHONY- SPECIFICATION forming part of Tletters Patent No. 537,282, dated April 9,1895. A Application filed December 20, 1894. Serial No. 532,426. (No model.)

I of the United States, residing at Washington,

in the District of Columbia, have invented certain new and useful Improvements in Telephony; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to telephony.

The object of this invention is to secure a current of sufficient potential to effect the telephonic transmission of speech without employing the Ruhmkorfi induction-coil.

The invention consists in the employment of the so-called extra current for this purpose.

The invention consists particularly, in the combination, in a telephone system, with the microphonic transmitter of an extra current or spark-coil.

Various methods of combination of these factors are illustratedin the accompanying diagrammatic figures.

Figures 1 and 2 represent one method of combination, Fig. 1 representing thejline as a closed metallic circuit, Fig. 2 representing it as a grounded or earth circuit. Figs. 3 and at represent another method of combination, Fig. 3 representing the line as a closed metallic circuit, Fig. at representing it as a grounded or earth circuit. resent the combination of the above two methods, Fig. 5 representing theline as a closed metallic circuit, Fig. 6 representing it as a grounded or earth circuit.

In each figure, two distinct telephonic stations A and'B are represented connected by the line C.

In Figs. 1 and 2, at station A, the apparatus employed is a galvanic battery a, a spark or extra-current coil a a microphone a and and a receiving telephone a These instruments are. connected in parallel across the line C so that the microphone a short circuits the galvanic battery current from a through the coil a across the line C. The receiving telephone a is looped in the line (J beyond the short-circuit. At station E the above is duplicated with markings 12,19 b b for the corresponding parts.

Figs. 5 and 6 rep- In Figs. 3' and 4, at station A, the same apparatus is used. In this combination, however, the instruments are connected in parallel across the line C in such manner that the coil 0. short-circuits the galvanic current from a through the microphone u across the line '0. The receiving telephone a is looped in the line 0 beyond the short-circuit. At station B the above is duplicated as before.

In Figs. 5 and 6, at station A, the combination employed at station A, Fig. 1 is used;

while at station B that employed at station A, Fig. 3 is used.

The operation of these combinations is as follows: By-means of the short-circuit across the line the galvanic current finds a path of low resistance through the coil and the microphone. This current through the coil can be modified in its strength by the action of the microphone. Every modification of the current strength of the galvanic current through the coil generates an extra current which may be of high potential if the coil beof proper construction.

This extra current, if of sufficiently high potential to overcome the line of resistance, discharges itself along the line to the distant station through the receiving telephone.

As represented and described, only two stations are shown on the line. However any desirable number may be placed thereon without involving any difierence in principle.

Having thus fully described my invention,

what I claim as new, and desire to secure by Letters Patent, isa 1. In a telephone system embracing a mi crophone transmitter, the combination therewith of an extra-current or sparkcoil, substantially as and for the purpose described.

2. In a telephone system embracing a microphone, the combination therewith of an extra-current or spark coil, the two being in parallel across the line circuit, substantially as and for the purpose set forth.

In testimony whereof I affix my signature in presence of two witnesses. j i

ELLIS F. Fnosr.

Witnesses a R. G. DYRENFORTH, E. H. PARRY. 

